[HN Gopher] Averaging is a convenient fiction of neuroscience
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       Averaging is a convenient fiction of neuroscience
        
       Author : domofutu
       Score  : 25 points
       Date   : 2024-09-23 21:41 UTC (1 hours ago)
        
 (HTM) web link (www.thetransmitter.org)
 (TXT) w3m dump (www.thetransmitter.org)
        
       | glial wrote:
       | All models are convenient fictions. I heard a neuroscientist once
       | describe averaging as a low-pass filter. People know it hides
       | high-frequency dynamics. But unless you have a way to interpret
       | the high-frequency signal, it looks an awful lot like noise.
        
         | sroussey wrote:
         | I think of summaries as the text equivalent of averaging. Some
         | high frequency stuff you don't want to loose in that case are
         | things like proper names, specific dates, etc. In the face of
         | such signal, you don't want to average it out to a "him" and a
         | "Monday".
        
         | heyitsguay wrote:
         | My grad school research was with an NIH neuroscience lab
         | studying low-level sensory processing that offered a
         | fascinating perspective on what's really going on there! At
         | least for the first few levels above the sense receptors in
         | simpler animal models.
         | 
         | To oversimplify, you can interpret gamma-frequency activity as
         | chunking up temporal sensory inputs into windows. The specific
         | dynamics between excitatory and inhibitory populations in a
         | region of the brain create a gating mechanism where only a
         | fraction of the most stimulated excitatory neurons are able to
         | fire, and therefore pass along a signal downstream, before
         | broadly-tuned inhibitory feedback silences the whole population
         | and the next gamma cycle begins. Information is transmitted
         | deeper into the brain based on the population-level patterns of
         | excitatory activity per brief gamma window, rather than being a
         | simple rate encoding over longer periods of time.
         | 
         | Again, this is an oversimplification, not entirely correct,
         | fails to take other activity into account etc etc, but I'm
         | sharing it as an example of an extant model of brain activity
         | that not only doesn't average out high-frequency dynamics, but
         | explicitly relies on them in a complex nonlinear fashion to
         | model neural activity at the population level at high temporal
         | frequency in a natural way. And it's not completely abstract,
         | you can relate it to observed population firing patterns in,
         | e.g., insect olfactory processing, now the we have the hardware
         | to make accurate high-frequency population recordings.
        
         | jtrueb wrote:
         | It is a low-pass filter in the frequency domain with a roll-off
         | that is not smooth. I quite like [1] as a quick reference.
         | 
         | https://www.analog.com/media/en/technical-documentation/dsp-...
        
       | UniverseHacker wrote:
       | I've become increasingly convinced that the idea of averaging is
       | one of the biggest obstacles to understanding things... it
       | contains the insidious trap of feeling/sounding "rigorous" and
       | "quantitative" while making huge assumptions that are extremely
       | inappropriate for most real world situations.
       | 
       | Once I started noticing this I can't stop seeing this almost
       | everywhere- almost every news article, scientific paper, etc.
       | will make clearly inappropriate inferences about a phenomenon
       | based on the exact same mistake of confusing the average for a
       | complete description of a distribution, or a more nuanced
       | context.
       | 
       | Just a simple common example, is the popular myth that ancient
       | people died of old age in their 30s, based on an "average life
       | span of ~33 years" or such. In reality the modal life expectancy
       | of adults (most common age of death other than 0) has been pretty
       | stable in the 70s-80s range for most of human history- the low
       | average was almost entirely due to infant mortality.
       | 
       | The above example is a case where thinking in terms of averages
       | causes you to grossly misunderstand simple things, in a way that
       | would be impossible even with basic common sense in a person that
       | had never encountered the idea of math... yet it is a mistake you
       | can reliably expect people in modern times to make.
        
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